What it does
The gentlest class of chemical exfoliant. Large PHA molecules work only at the surface, smoothing texture and brightening dullness with minimal sting, while also acting as humectants and antioxidants.
Best for
Sensitive, reactive, or rosacea-prone skin that cannot tolerate AHAs, and anyone starting chemical exfoliation.
What are PHAs?
PHAs, or polyhydroxy acids, are the gentlest class of chemical exfoliants, led by gluconolactone. Their large molecules work only at the skin surface, so they smooth texture and brighten dullness with minimal sting.
Unusually, PHAs also hydrate and act as antioxidants, which no other exfoliant class does as well.
What does gluconolactone do for skin?
Gluconolactone exfoliates gently, hydrates, and adds antioxidant protection.
Research on gluconolactone shows it exfoliates gently and protects against UV-induced damage in laboratory models, alongside its humectant effect.
It is gentler than glycolic acid, lactic acid, and even mandelic acid, which makes it the entry point for reactive skin. Use it at night and keep sunscreen in the morning routine.
Who should use PHAs?
PHAs suit sensitive, reactive, rosacea-prone, or exfoliation-newbie skin. If your skin tolerates acids well and you want faster resurfacing, an AHA like glycolic acid works harder.
Evidence
Gluconolactone, the leading polyhydroxy acid, exfoliates gently, hydrates, and has shown antioxidant activity including protection against UV-induced damage in laboratory models.
Read the source: Dermatologic Surgery: the polyhydroxy acid gluconolactone protects against ultraviolet radiation in vitro (2004) ->